Process of inhibiting precipitation by the use of phosphorus compounds containing the atom skeleton p-(c-p){11 {0 or p-(c-p){11

ABSTRACT

Phosphorus compounds containing the skeleton P-(C-P)2 or P-(CP)3 of the formula P(O)a(R1)b(CH P(O)(R2)R3)3 b and method for making by reacting a compound of the formula P(O)a(R1)b(CH2Cl)3 b with a compound of the formula P(R5)(R6)OR4 to split off R4C1. Also uses of the products as threshold agents, sequestering agents, detergent composition additives, peroxy solution stabilizers and chlorine releasing agent stabilization is claimed.

United States Patent [72] lnventor Ludwig Maier Tiergartenstrasse l7,Kilchberg, Zurich, Switzerland 21 Appl. No. 7,429 [221 Filed 195 151 "WM[23] Division of Ser. No. 690,418

0 c. 14,1967 Patented Nov. 2, 1971 [54] PROCESS OF INHIBITINGPRECIPITATION BY THE USE OF PIIOSPIIORUS COMPOUNDS CONTAINING THE ATOMSKELETON P-(C-P) OR P-(C-P) 13 Claims, No Drawings [52] US. Cl 210/58,252/180, 260/502.4 51 Im. Cl C02b 5/06 [50] Field of Search... 260/932,

[56] References Cited UNITED STATES PATENTS 3,332,986 7/1967 Block et al260/500 3,422,137 1 1969 Quimby 260/5024 3,451,939 6/1969 Ralston 210/58X Primary Examiner-Michael Rogers Att0rneysJohn D. Upham, Joseph D.Kennedy and L. Bruce Stevens, Jr.

PROCESS OF INHIBIIING PRECIPITATION BY THE USE OF PIIOSPI'IORIJSCOMPOUNDS CONTAINING THE ATOM SKELETON P-(C-P) OR P-(C-P) Thisapplication is a division of application, Ser. No. 690,4l8,filed Dec.14, 1967.

This present invention relates to phosphorus compounds containing theatom skeleton P-C-P), or P-(C-P) and corresponding to the generalformula in which R, R, and R signify possibly substituted and/orethylenically or acetylenically unsaturated hydrocarbon groups orheterocyclic groups attached through a carbon atom, R groups where R isthe group of a hydroxyl compound, IIO groups, M0 groups where M is ametal atom, ammonium or substituted ammonium, and preferably at leastone R0, H0, or M0 group is present, a signifies 0 or 1, and b 0 or 1, toa process for preparing these compounds and to compositions containingthese compounds. Normally, each R group, i.e., R, R, R, etc., will havenot more than 24 and for some use not more than eight carbon atoms.

The process is characterized in that a bis-chloro-methylphosphoruscompound or a tris-chloromethyl-phosphorus compound of the generalformula in which R, a and b have the same significance as above, and aphosphorous acid triester, phosphonous acid diester or phosphinous acidester of the general formula in which R and R' have the samesignificance as R and R above except not being H0 or M0 groups and Rsignifies an aliphatic, cycloaliphatic or araliphatic hydrocarbon group,whose chlorine derivative RCl is volatile at the reaction temperatureand the pressure employed are brought to reaction at a temperaturebetween about 140 and 200 C., the hydrocarbyl chloride formed as abyproduct is continuously removed, possibly under reduced pressure fromthe reaction mixture, the ester groups present in the formed product canbe converted to the corresponding acid groups in known manner and theacid groups can be converted to the metal salts, ammonium salts orsubstituted ammonium salts in known manner.

Assays for preparing compounds showing the atom skeleton P-(C-P) byreaction of (RO)(O)P(CH Cl) with NaP(O) (OC)zH have been unsuccessful[US Air Force Technical Report, Contract AF 33 (616)-6950 (1960)]. Otherindications dealing with the preparation of corresponding phospho-.

rus compounds showing the atom skeleton P-(C-P) OR P- (c lfl are notfound in the prior art.

As compared with the already known methylene-bisphosphonic acids andtheir esters and salts, the compounds of invention possess the atomskeleton P-(C-P), or P-(C-P) and may contain up to six ester groups orhydroxyl groups attached to the phosphorus atoms. By this, they aresuperior in respect of their qualities and possibilities of application.If they bear similar groups the novel esters, for example, showgenerally higher boiling points and consequently to the extent that theyare liquids, also a wider liquid range. The complexing power, theemulsifying or dispersing ability and the thermal resistance are betteras compared with the well-known compounds. Therefore, they are bettersuited for utilizations such as complexing agents, surfactants,plasticizers, hydraulic fluids, corrosion inhibitors, stabilizers forperoxides and hydroperoxides, additives to electrolytic baths, heattransfer agents, lubricants, oil additives, gasoline additives andadditives to detergents, and they provide technical advantages.

Some of the compounds of invention having ester groups are soluble inwater as long as the alcohol group does not possess more than threecarbon atoms. The acids formed by hydrolysis of the ester groups can beused in aqueous solution in the form of salts, e.g., sodium salts,potassium salts and amine salts. They can form soluble complexes withcertain metals such as calcium, magnesium, iron, copper, lead, silver,uranium. However, such complexes are also formed by the compounds ofinvention containing two or more ester groups instead of hydroxylgroups. In general, the complexing power increases with the number ofester groups or hydroxyl groups.

The novel phosphine oxides, e.g.tris-(0,0'-diethylphosphonylmethyl)-phosphine oxide andbis-(0,0'-diethylphosphonylmethyl)-methylphosphine oxide, display anunusual absorption capacity in that they bind a multiple of their weightof many solvents or organic liquids so strongly that a gel is formedsimilar to the solutions of certain polymers (cf. Example 3). Suchphosphine oxides therefore are especially suited for the fixation ofcertain liquid compounds, e.g. essential oils and plasticizers.

The reactions leading to the novel compounds proceed according to theequation The bis-chloromethyl-phosphorus' compounds andtrischloromethyl-phosphorus compounds referred to first are phosphines,phosphine oxides and phosphinic acid esters containing two or threechloromethyl groups linked to the phosphorus atom. If only twochloromethyl groups are present, there is attached a further organicgroup via a carbon atom or oxygen atom to the phosphorus atom.

Suitable organic phosphines are, for example trischloromethyl-phosphine,bis-chloromethyl-methylphosphine, bis-chloromethyl-vinylphosphine,bis-chloromethyl-npropylphosphine, bis-chloromethyl-iso-amylphosphine,bischloromethyl-B-butynylphosphine, bis-chloromethyldodecylphosphine,bis-chloromethyl-cyclopentylphosphinebis-chloromethyl-pentafluorocyclohexylphosphine,bischloromethyl-benzylphosphine, bis-chloromethyl-cinnamylphosphine,bis-chloromethyl-tolylphosphine.

Suitable phosphine oxides are, for example, trischloromethylphosphineoxide, bis-chloromethyl-ethylphosphine oxide,bis-chloromethyl-ethynylphosphine oxide, bischloromethyl-allylphosphineoxide, bis-chloromethyl-tert-butylphosphine oxide,bis-chloromethyl-3-cyclopentenylphosphine oxide,bis-chloromethyl-cyclooctylphosphine oxide,bischloromethyl-styrylphosphine oxide, bis-chloromethyldimethylaminophenylphosphine oxide.

Tris-chloromethyl-phosphine can be prepared in the following way:Tetrakis-hydroxymethyl-phosphonium chloride is converted by phosphoruspentachloride in carbon tetrachloride to thetetrakis-chloromethyl-phosphonium chloride, and the latter is decomposedby sodium bicarbonate and the intermediate to be used herein isextracted by ether [A. l-Iofiman,.l.A.C.S. 52, 2995 (1930)].

For the preparation of tris-chloromethyl-phosphine oxide which is afurther starting compound in the instant process, thetris-chloromethyl-phosphine is converted by treating with the calculatedamount of bromine to the tris-chloromethyldibromophosphoran, the latteris decomposed by water and sodium hydroxide and thetris-chloromethyl-phosphine oxide is extracted with a solvent, e.g.benzene.

Further starting compounds can be prepared, for example, by reactingbis-chloromethyl-chlorophosphine or bischloromethyl-phosphinic acidchloride with a Grignard compound. Thus, the choice of the organic groupR, if being a hydrocarbyl or heterocyclic group, depends on theavailable Grignard compounds. The numerous possible substituentstherefore do not have to be enumerated specifically.

The bis-chloromethyl-phosphinic acid esters serving as further startingcompounds can be prepared, for example, as follows: At first,bis-chloromethyl-phosphinic acid chloride is prepared in known mannerIK. Moedritzer, .l.A.C.S. 83, 438 l (1961)]. This compound can beprepared especially conveniently by heating bis-hydroxymethyl-phosphinicacid with excess thionyl chloride. The chlorine atom being attached tothe phosphorus atom is subsequently exchanged for anester group byreacting expediently in the presence of a tertiary amine with a hydroxylcompound able to be esterified. Thus, the choice of the organic group R,if an R group, depends on the available alcohols, phenols andheterocyclic hydroxyl compounds which are capable of being esterifiedwith phosphinic acid. The number of suitable compounds and possiblesubstituents is very great.

Suitable phosphinic esters are, e.g. bis-chloromethyl-phosphinic acidmethylester, bis-chloromethyl-phosphinic acid isopropylester,bis-chloromethyl-phosphinic acid decylester, bis-chloromethyl-phosphinicacid benzylester, bischloromethyl-phosphinic acid p-fluorophenylester,bischloromethyl-phosphinic acid 3-allylphenylester.

Phosphorous acid triesters, phosphonous acid diesters and phosphinousacid esters, as they have been formulated in the equation above, serveas further reactants. These starting compounds can be prepared accordingto well-known processes [Kosolapofi', Organophosphorus Compounds I950;phosphites: p. 184-187; phosphonites and phosphinites: p. 358-359; andl-louben Weyl, Tome Xll/l and 2]. The number of suitable phosphites isgreat.

There are known, for example, phosphites whose ester groups on thephosphorus atom are alike or different and where R in the RO group canbe, for example, one of the following groups: methyl, ethyl, propyl,iso-propyl, butyl, iso-butyl, iso-amyl n-hexyl, n-heptyl, n-octyl,2-0ctyl, n-hexadecyl, Z-decahydronaphthyl, menthyl, benzyl,diphenylmethyl, 4- phenylethyl-phenylethyl, 2.-[ l,3-bis-p(m oro)-tolyl]-propyl, phenyl, biphenylyl, lor Z-naphthyl,2,2(l,l'-dinaphthylyl), l-anthryl, cholesteryl, 2-, 3- or 4-tolyl,pseudocumyl, p-tertbutylphenyl, o-cyclohexylphenyl and 2-(4-methyl-5-thiazolyl)'ethyl.

These groups can also hear substituents. Known examples are2-chloroethyl, l-trifluoromethyl-ethyl, l-carbethoxylethyl,tert-butylnitril, a-carbethoxybenzyl, 2- and 4- chlorophenyl,pentachlorophenyl, 2-methoxyphenyl, 4-

nitrophenyl, Z-trichloromethylphenyl, 2-trichloromethyl-4,6-dichlorophenyl, 2,4,6-tris-trichloromethyl-phenyl and 1-(2,4-dibromo)-naphthyl.

These groups, moreover, can also be unsaturated. Known examples areallyl, l-iodoallyl and 4-allyl-2-methoxyphenyl.

Moreover, two ester groups on the same phosphorus atom can be linkedtogether. Such ester groups are derived from diols, like1,2-dihydroxyethane, 1,3-dihydroxypropane, 1,2- dihydroxypropane,ortho-hydroxybenzyl alcohol, pyrocatechin and orthodihydroxypyridine If,for the sake of simplicity herein, these compounds are called0,0'-diorgano compounds such kinds of 0,0'-cyclo compounds will beincluded. R and R accordingly also signify groups of hydroxyl compoundswhich are esterifiable with phosphinic acid, phosphorus acid,phosphonous acid and phosphinous'acid.

The phosphonous acid diesters contain one organic group and thephosphinous acid esters two organic groups which are linked via a carbonatom to the phosphorus atom. They can be the same groups as have beenenumerated for the bischloromethyl-phosphines andbis-chloromethyl-phosphine oxides. In the reaction of an organicphosphite, phosphonite or phosphinite, one of the ester groups must beable to undergo the Arbuzov-Michaelis reaction. Thus, one of these estergroups has only an auxiliary function and its organic constituent R willbe split off as chlorohydrocarbon. In order to avoid undesiredbyproducts, the chlorohydrocarbon should be removed continuously fromthe reaction mixture. It therefore will be volatile at the reactiontemperature.

' R preferably possesses one to four carbon atoms so that the alkylchloride formed will very fast escape from the reaction mixture at thereaction temperature. If necessary, the reaction can be carried outunder reduced pressure.

The process is carried out preferably at about 140 to 180 C. Theapplication of higher temperatures is less desirable in view of possibleside reactions which may lead to undistillable polymeric compounds. Ingeneral, about 200 C. should not be exceeded. The reaction can beobserved and controlled by determining the alkyl chloride evolving fromthe reaction mixture. It is advantageous to use excess phosphorous acid,phosphonous acid or phosphinous acid which acts as a solvent and can berecovered by distillation. The reaction may also be performed in aninert solvent. High boiling hydrocarbons such as xylene, decalin,methylnaphthalene and ethylnaphthalene are suitable for this purpose.The reaction is expediently carried out in an inert atmosphere, e.g.,nitrogen, if easily oxidizable trivalent phosphorus compounds arereacted.

The manufacture of the corresponding acids can be achieved by acidhydrolysis, e.g., by hydrochloric acid. A particular advantageous methodfor preparing the acids is based on the thermal decomposition of thecorresponding isopropyl esters. Propylene is split off quantitatively atabout I C. leaving the acid in percent yield.

The acids can be added in the form of alkali salts or salts of organicbases to the usual liquid or solid detergents and rinsing agents andthey can replace totally or partly the complexing agents such as sodiumtripolyphosphate, sodium hexametaphosphate, trisodium nitrilotriacetate, tetrasodium ethylenediamine tetracetate, tetrasodiummethylene diphosphonate, tetrasodium hydroxyethylidene diphosphonate,etc. used until now. The hexasodium salt oftris-(dihydroxyphosphonylmethyl)-phosphine oxide, for example, iscapable of binding calcium about three times as much as sodiumtripolyphosphate under the same conditions. Moreover, the thermalresistance and partly also the hydrolytic resistance are substantiallygreater in comparison to complexing agents employed up to now. Thesurface active compounds contain expediently a straight-chain alkylgroup showing about 10 to 18 carbon atoms.

The uses of the new compounds of the invention are further illustratedin detail as follows:

THRESHOLD AGENTS Most commercial water supplies contain alkaline earthmetal cations, such as calcium, barium, magnesium, etc. and severalanions, such as bicarbonate, carbonate, sulfate, oxalate, phosphate,silicate, fluoride, etc. When combinations of these anions and cationsare present in concentrations which exceed the solubility of theirreaction products, precipitates form until these product solubilityconcentrations are no longer exceeded. For example, when theconcentrations of calcium ion and carbonate ion exceed the solubility ofthe calcium carbonate reaction product, a solid phase of calciumcarbonate will form.

Solubility product concentrations are exceeded for various reasons, suchas evaporation of the water phase, change in pH, pressure ortemperature, and the introduction of additional ions which forminsoluble compounds with the ions already present in the solution.

As these reaction products precipitate on the surfaces of thewater-carrying system, they form scale. The scale prevents effectiveheat transfer, interferes with fluid flow, facilitates corrosive processand harbors bacteria. This scale is an expensive problem in manyindustrial water systems causing delays and shutdowns for cleaning andremoval.

Scale-forming compounds can be prevented from precipitating byinactivating their cations with chelating or sequestering agents so thatthe solubility of their reaction products is not exceeded. Generally,this requires many times as much chelating or sequestering agent ascations and these amounts are not always desirable or, economical.

It is well known in the art that certain inorganic polyphosphates willprevent such precipitation when added in amounts for less than theconcentrations needed for sequestering or chelating. When aprecipitation inhibitor is present in a potentially scale-formingsystem, at a markedly lower concentration than that required forsequestering the scale-forming cations, it is said to be present inthreshold amounts. Generally, threshold inhibition takes place at aweight ratio of threshold active compound to scale-forming cationcomponents of less than about 0.5 to 1.0. When the scale-formingcompound is alkaline earth metal, carbonate, sulfate, oxalate,phosphate, fluoride or silicate, the novel compounds of the presentinvention will inhibit their precipitation from solution when added tothe solution in threshold amounts of up to about 100 parts by weight permillion parts of water, preferably up to about 25 parts per million formost commercial purposes.

The threshold" concentration range can be demonstrated in the followingmanner. When a typical scale-forming solution containing the cation of arelatively insoluble compound is added to a solution containing theanion of the relatively in-' soluble compound and a very small amount ofa threshold active inhibitor, the relatively insoluble compound will notprecipitate even when its normal equilibrium concentration has beenexceeded. if more of the threshold active compound is added, aconcentration is reached where turbidity or a precipitate of uncertaincomposition results. As still more of the threshold active compound isadded, the solution again becomes clear. This is due to the fact thatthreshold active compounds in high concentrations also act assequestering agents. Thus, there is an intermediate zone between thehigh concentrations at which threshold active compounds sequester thecations of relatively insoluble compounds and the low concentrations atwhich they act as threshold inhibitors. Therefore, one could also definethreshold" concentrations as all concentrations of threshold activecompounds below that concentration at which this turbid zone orprecipitate is formed.

The polyphosphates are generally efi'ective threshold inhibitors formany scale-forming compounds at temperatures below 100 F but afterprolonged periods at higher temperatures, they lose some of theireffectiveness. Moreover, in an acid solution, they revert to ineffectiveor less effective compounds.

The novel compounds of the present invention which are especiallysuitable as threshold agents include compounds of the formulas Forexample, tris(methyl phosphonic acid) phosphine, tris(methyl phosphonicacid) phosphine oxide, the monosodium salt of tris(methyl phosphonicacid) phosphine, disodium salt of tris(monophosphonic acid) phosphineoxide, the hexapotassium salt of tris(monophosphonic acid) phosphine,hexalithium salt of tris(monophosphonic acid) phosphine. Not only arethese compounds efiective inhibitors at room temperatures but they arealso effective at elevated temperatures. Moreover, they retain theireffectiveness in acid and salt solution.

SEQUESTERING AGENTS It is well understood that generally the ability ofa sequestering agent to sequester or inhibit the precipitation of metalions effectively is dependent upon the particular metal ion and the pHadditions. For example, a sequestering agent which is usually consideredquite effective in sequestering a particular metal ion in an alkalinesolution is usually found to be markedly less effective toward the sameor another metal ion in an acid solution. In addition, it has usuallybeen found that many sequestering agents are really only truly effectivetoward a particular metal ion within a narrow pH range. An outstandingexample of this is the ability of the sequestering agent (sodiumgluconate) to effectively sequester the ferric ion only at a pH of about12 or above. As can be appreciated, therefore, sequestering agents whichare effective toward many and various metal ions over a wide range of pHvalues would be an advancement in this art.

The novel compounds of the present invention are effective sequesteringagents for metal ions in an aqueous solution and include, for example,compounds of the following general formulas:

Suitable specific compounds are illustrated by those named above underthreshold agents. The sequestering agents of the present inventionexhibit, in addition to their sequestering ability, such advantageousproperties as being hydrolytically stable, that is having a substantialresistance to hydrolysis or degradation under varying pH andtemperatures and relatively inert or noncorrosive to metals such aszinc, copper, aluminum and the like.

The amount of the sequestering agent necessary to be effective varieswith, inter alia, the type and amount of problem metal ions, pHconditions, temperature and the like but in any event, only minoramounts are usually sufiicient. The amount used in the present inventionvaries from about l00 p.p.m. to about 5,000 p.p.m. at a pH from about 8to l2.

In order to illustrate the sequestering ability of the novel compoundsof the present invention, the following tests and comparisons were madewith the indicated results.

One gram of the novel compound of the present invention is dissolved inan aqueous solution containing 2,000 parts per million of NA,CO, andtitrated to a cloudy endpoint with 0.25 M calcium acetate at a pH of lland a temperature of 25 C. Data is given in the table 1 below:

Sodium tripolyphosphate (S.T.P.) 250 As can be seen from table I, thenovel compounds of the present invention have a superior sequesteringability than that of the S.T.P.

DETERGENT BUILDERS The sequestering agents of the present invention maybe advantageously employed as builders and when thus employed can beused with any of the conventional detergents classed as syntheticnonsoap anionic, nonionic and amphoteric surface active compounds andmixtures thereof. Anionic surface active compounds such as a fattyalcohol, fatty acid, sterol, a fatty glyceride, a fatty amine, an arylamine, a fatty mercaptan, tall oil, etc. Nonionic surface active agentsalso include those products produced by condensing one or morerelatively lower alkyl alcohol amines such as methanolamine,ethanolamine, propanolamine, etc. with a fatty acid such as lauric acid,cetyl acid, tall oil fatty acid, etc. to produce the corresponding acid.Other advantageous nonionic surface active agents are condensationproducts of a hydrophilic compound having at least one active hydrogenatom and a lower alkylene oxide. For example, the condensation productof an aliphatic alcohol containing from about eight to about 18 carbonatoms and from about 3 to about 30 moles of ethylene oxide per mole ofthe alcohol or the condensation products of an alkyl phenol containingfrom about eight to about 18 carbon atoms in the alkyl group and fromabout 3 to about 30 moles of ethylene oxide per mole alkyl phenol.

Amphoteric surface active compounds can be described as compounds whichhave both anionic and cationic groups in the same molecule. Suchcompounds may be grouped into classes corresponding to the nature of theanionic forming group which is usually carboxy sulfo or sulfato.Examples of such compounds include sodium-N-coco-compounds which can bebroadly described as compounds containing hydrophilic or lyophilicgroups in their molecular structure and ionized in an aqueous medium togive anions containing the lyophilic group. These compounds include thesulfated or sulfonated alkyl or aryl or alkyl aryl hydrocarbons andalkaline metal salts thereof. For example, sodium salts of long chainalkyl sulfates, sodium salts of alkyl naphthalene sulfonic acid, sodiumsalts of sulfonates abietenes, sodium salts of alkylhenzene sulfonicacids, particularly those in which the alkyl group contains from eightto 24 carbon atoms, sodium salts of sulfonated mineral oils and sodiumsalts of sulfosuccinic acid esters such as sodium dioctylsulfosuccinate.

Nonionic surface active compounds can be broadly described as compoundswhich do not ionize but usually acquire hydrophilic characteristics froman oxygenated side chain, suchas polyoxyethylene while the lyophilicpart of the molecule may come from fatty acids, phenols, alcohols,amides or amines. Examples of nonionic surface active agents includeproducts formed by condensing one or more alkylene oxides of two to fourcarbon atoms such as ethylene oxide or propylene oxide, preferablyethylene oxide alone or with other alkylene oxides with a relativelyhydrophobic beta amino propionate, sodium-N-lauryl betaiminodipropionate and the like. Other typical examples of thesecategories of the anionic, nonionic and/or amphoteric surface activeagents are described in Schwartz and Perry, Surface Active Agents,lnterscience Publishers, New York (1949).

The amount of builder necessary to be used with the surface activecompound described hereinbefore may vary depending upon the end use typeof active agent employed, pH conditions and the like. In general, thebuilders of the present invention can be employed in detergentcompositions in any desired proportions which are effective, that is,which enhance the detergency characteristics of the surface activecompound. Generally, these amounts vary from about l0 percent by weightto about 90 percent by weight of a detergent composition.

In order to illustrate the invention, a tris( methyl phosphonic acid)phosphine oxide builder was compared under carefully controlledconditions with sodium tripolyphosphate for building properties in hotwater. The conditions of the test were: total detergentconcentration0.l6 percent; temperature 60 C.; pH-9.5. The tests weremade in a Launder-Ometer machine on standard soiled fabric specimens.

The following detergent compositions were used in the test with thepercentages being by weight in the aqueous washing solution:

*Tris(methyl phosphonic acid) phosphine oxide HOZP(CH2P03H2)2J- TABLE I]Builder Soil Removal 1. Tris(methyl phosphonic acid) phosphinc oxide 2.Sodium tripolyphosphate 3. No builder present The above results indicatethat a builder of the present invention compares very favorably withsodium tripolyphosphate, a widely used builder. Therefore, it can beappreciated that the new detergent builders of this invention exhibitbuilding properties comparable or better to conventional widely usedbuilders and can be used advantageously in many applications where theconventional builders are not suitable.

The novel compounds of the present invention can be used as detergentactive agents in a built detergent composition. Water-soluble inorganicbuilders, water-soluble organic builders or mixtures thereof can be usedto enhance the detergency of the present novel compounds. These buildersinclude, for example, the conventional alkali metal polyphosphates,i.e., the tripolyphosphate and pyrophosphate (sodium tripolyphosphate,tetrasodium polyphosphate, tetrapotassium phosphate, disodiumpyrophosphate and the like); the amino polycarboxylic acids and saltssuch as the sodium, potassium and ammonium salts of nitrilotriaceticacid, the sodium, potassium and ammonium salts of amino tri(methylenephosphonic acid) as well as the free acid and the diphosphonic acids andsalts. Generally speaking, the amount of the novel compounds used as anactive ranges from about l0 percent by weight to about percent by weightof a detergent composition.

The detergent compositions of the present invention can be prepared inany of several commercially desirable composition forms such as bar,granular, plate, liquid and tablet form.

STABILIZATION OF PEROXY SOLUTIONS The use of a stabilizing agent tominimize the decomposition of the peroxy compound is well established inthe peroxy bleaching art because, among other things, the oxygenreleased by the decomposition of the peroxy compound in general has nobleaching action as contrasted with the normal autodecomposition of theperoxy compound which does function as a bleaching agent. In fact, thedecomposition of the peroxy compound may be harmful. For example,cellulosic materials in strongly alkaline peroxy solutions are attackedby the oxygen from decomposition with the result of loss of strength bythe materials. ln-general, stabilizing agents are of various and diversenature and the ability of a material to be an effective stabilizingagent is apparently unpredictable. For example, although a fewsequestering agents such as sodium pyrophosphate can be considered asstabilizing agents, the majority of sequestering agents are notconsidered to be effective stabilizing agents while such nonsequesteringmaterials as sodium stannate and sodium silicate have been reported asbeing effective stabilizing agents. Therefore, due to theirunpredictability and their diverse nature, the stabilizing agents forperoxy solutions vary in their ability with changes in the prevailingconditions such as pH, temperature conditions and the like of the peroxysolutions. For todays bleaching conditions, the stabilizing agent shouldpreferably be effective in alkaline solutions and under relatively hightemperature conditions which are frequently encountered in practice aswell as being compatible with other additives usually present in theperoxy bleaching solutions such as optical whiteners, that is,brighteners or fluorescent white dyes, wetting agents and the like. Ithas been found that the novel compounds of the present invention havingthe following general formula are effective establishing agents forperoxy solutions as will more fully be discussed hereinafter. Compoundsillustrative of the invention are named above under threshold agent.

The stabilizing agents of the instant invention exhibit, in addition totheir stabilizing ability, the highly beneficial propertics of beinghighly water soluble and hydrolytically stable,

that is having a substantial resistance to hydrolysis or degradationunder various pH and temperature conditions.

Peroxy solutions which are capable of being stabilized in addition tohydrogen peroxide and its addition compounds, such as the peroxide ofsodium and the super oxide of potassium, include urea percompounds,perborates, persulfates and the peracids such as persulfuric acid,peracetic acid, peroxy monophosphoric acid and their water-soluble saltcompounds such as sodium, potassium, ammonium and organic amine saltsvDepending upon, inter alia, the particular peroxy-compound used, the pHof the aqueous peroxy solution is usually adjusted with inorganic alkalimetal basic materials, such as sodium hydroxide, sodium carbonate,sodium silicate, di and trisodium phosphates and the like, includingmixtures of these as well as the potassium forms of the foregoingmaterials, to a pH of between about 7.5 and about 12.5. Usually if thepH is higher than about 12.5 rapid bleaching occurs and theperoxycompounds rapidly decompose so that it is difficult to control aproper bleaching rate without undue damage to the fibers. At pH valueslower than about 7.5, the rate of bleaching in most cases is slow to theextent of being uneconomical for bleaching.

The concentration in peroxy solutions can vary depending upon, interalia, the type of peroxy-compound, pH, temperature, type of bleachingdesired and the like, however, normal concentrations, i.e. from about0.01 to about percent can be used with concentrations from about 0.2 toabout 3 percent being preferred.

The stabilizing agents of the present invention may be dissolved in theperoxy solution which is ready for use or may be incorporated in aconcentrated peroxy solution, such as a 35 percent solution of hydrogenperoxide, which is usually further diluted to form the peroxy solutionfor bleaching. In addition, the stabilizing agent can be incorporated indry bleach compositions, such as perborate compositions, by admixingtherewith and the resulting composition dissolved in the aqueous systemimmediately preceding its end use application. in any event, thestabilizing agent is intended to be used with the peroxy solution at thetime of its use for bleaching purposes.

The concentration of the stabilizing agent of the present invention inthe peroxy solution can vary depending upon, inter alia, concentrationof the peroxy solution, type of peroxycompound used, pH, temperature andthe like and usually for normal concentrations of peroxy solutions andwith conventional bleaching methods, the stabilizing agent is preferablypresent in concentrations from about 0.001 to about 5 percent with fromabout 0.1 percent to about 1 percent being especially preferred.

STABILIZATION OF CHLORINE RELEASING AGENTS The novel compounds of thepresent invention can be used to stabilize chlorine releasing agents insolution to prevent their decomposition. The chlorine releasing agentswhich are suitable for use are those water-soluble organic and inorganiccompounds which are believed to have oxidizing power by virtue ofcontaining available-chlorine" which can react in aqueous solution toform hypochlorous acid or the hypochlorite ion. Such organic compoundsinclude the alkyl hypochlorites and especially the lower alkylhypochlorites, such as ethyl hypochlorite, propyl hypochlorite, n-butylhypochlorite and tert-butyl hypochlorite; the N-chlorinated heterocycliccompounds and especially the five and six membered N-chlorinatedheterocyclic compounds, such as, hydantoin, N-chlorosuccinimide and thetriazines, such as the cyanuric acids and salts which includetrichloroisocyanuric acid, dichloroisocyanuric acid, sodiumdichloroisocyanura'te and potassium dichloroisocyanurate,polychlorocyanurate complexes as disclosed and described in U.S. Pat.Nos. 3,035,054; 3,035,056; 3,035,057; 3,150,132 and 3,072,654 such asl(monotrichloro)tetra-(monopotassium dichloro) pentaisocyanurate] aswell its melamine, ammeline and ammelide; and the N-chloro aromatic andsubstituted aromatic sulfonamides, such as sodium benzenesulfochloroamide, sodium nitrobenzenesulfochloroamide and sodiump-toluenesulfonchloroamide. Such inorganic compounds include the alkalimetal chlorine-containing compounds, such as sodium hypochlorite, sodiumchlorite and lithium hypochlorite, the alkaline earth metalchlorine-containing compounds, such as calcium hypochlorite and bariumhypochlorite and the chlorinated trisodium phosphates, a class ofcompounds which consist of physicochemical combination in unitarycrystalline form of trisodium phosphate and sodium hypochlorite. Thechlorinated trisodium phosphates" are known and are described along withtheir methods of preparation in US. Pat. Nos. 1,555,474 or 1,965,304.

The amount of stabilizer, i.e. novel compounds of the present invention,used to stabilize the chlorine releasing agents in solution can varyfrom about p.p.m. to about 5,000 p.p.m.

EXAMPLE 1 A mixture of 19.1 g. (0.1 mol) ot'C H O(O)P(CH.,Cl) (b.p.l04-110 C./l mm. n =1.48l2) and 66.4 g. (0.4 mol) of 9 shss sq st rrirsina nit s a msspl r a Analysis c u om, 394.23

Calcd% c 36.55 H 7.41 P 23.57 Found% c 35.40 H 7.44 P 22.23

EXAMPLE 2 A mixture of 24.5 g. (0.137 mol) of P(CH CI) and g. (0.9 mol)of P(OC H,-,) is refluxed in a nitrogen atmosphere (66 C.). After about12 hours the evolution of ethyl chloride is finished. (22.7 g. 86percent of ethyl chloride). There are formed two layers. The lower layersolidifies on cooling. According to infrared analysis and mixed meltingpoint with an authentic sample, it is OP[CH P(O)(OC H From the upperlayer crystallizes a small amount of OP(CH Cl) This is filtered off;m.p. 92-95 C. The distillation of the filtrate yields 80 g. (0.483 mol)of P(oc H The residue solidifies on cooling, yielding a waxylike mass.Yield 40.5 g. of P[CH P(O)(OC H 1 mp. 7888 C. The compound ishygroscopic.

On oxidation in known manner, e.g., on leading in air or 0x ygen, ontreating with hydrogen peroxide, etc. the correspondingtris-(0,0'-diethyl-phosphonylmethyl)-phosphine oxide is obtained.

Analysis C H OJ, (484.36)

Calcd% C 37.20 H 7.50 P 25.58

Found'k C 35.45 H 7.26 P 25.48

For the conversion to the free acid P[CH,P(O)(OH) 5 g. oftris-(0,0'diethyl-phosphonylmethyh-phosphine are heated with 20 ml. ofHCl 1:1 in a bomb tube at 200C. for 5 hours or are refluxed withconcentrated HCl. Upon evaporation there are obtained 3.7 g. (97percent) of the free acid as oily product. The acid can be titrated ashexabasic acid and shows breaks at pH 4.4 and 9.8 for 3 equivalentseach. Equivalent weight calculated 61.6, found 60.

EXAMPLE 3 A mixture of'25 g. (0.128 mol) of OP(CH,C1) and 130 g. i

(0.78 mol) of P(OC,l-1 is refluxed (l60l65 C.) until the evolution ofethyl chloride has finished. In about 6 hours, 21.8 g. (99 percent) ofethyl chloride are recovered. The residue solidifies completely uponcooling. It is now dissolved in 100 ml. of ethyl alcohol and 300 ml. ofether are added. The mix ture solidifies completely. No solvent can bepoured off. On pressure filtering, there are obtained 34.8 g. oftris-(0.0- diethyl-phosphonylmethyl)-phosphine oxide.- Ether is added tothe mother-liquor which is cooled to low temperatures and an additional5.5 g. of endproduct separate. Now the motherliquor is completelyconcentrated by evaporation and ether is added. An additional 8.1 g. ofendproduct separate. Yield 48.4 g. (75.5 percent) oftris-(0,0-diethyl-phosphonylmethy1)- phosphine oxide; m.p. 168-170 C.The product shows high absorption power. 8.1 g. absorb, for example,41.4 g. of triethyl phosphite which cannot be removed even under vacuum.48 g. dissolved in 100 ml. of ethanol and 300 ml. of ether added theretoyield a gel. A 2 percent solution of benzene also is totallygelatinized. No solvent can be decanted. The novel product absorbspreferentially benzene in a sytrene-benzene mixture 1:1).

The tri-chloromethyl-phosphine oxide serving as starting compound can beprepared in the following way: To 17.9 g. (0.1 mol) oftri-ch1or0methyl-phosphine in 100 ml. of benzene there are addeddropwise 16.0 g. (0.2 mol) of bromine. A yellow precipitate is formedconsisting of tri-chloromethyb dibromophosphoran, which is decomposed by1.8 g. of water. The precipitate dissolves and there are formed twolayers. For the neutralization there are added dropwise 8 g. of NaOHdissolved in 12 ml. of water and the brown-red solution becomescolorless. The benzene layer is separated and the water phase isextracted once more with benzene. From the benzene solution, afterevaporation, there are obtained 11.5 g. (59.0 percent) oftri-chloromethyl-phosphine oxide; m.p. 100101.5 C.

EXAMPLE 4 To a solution of 9.8 g. (0.05 mol) ofOP(CH Cl) in 100 ml. ofdecalin which is heated at 160 C. there are added dropwise, within 3hours, 25 g. (0.2 mol) of P(OCH The evolving methyl chloride iscontinuously removed from the mixture. The decalin and excess trimethylphosphite are distilled off under reduced pressure. The solid residue isrecrystallized fromv methanol-ether mixture. Yield 15 g. (75 percent) oftris- (0,0'-dimethylphosphonylmethyl)-phosphine oxide; m.p. l691 7 1 C.

For the conversion to the corresponding acid OP[CH P( O)(Ol-1) 150 g. oftris-(0,0-dimethyl-phosphonylmethy1)- phosphine oxide are refluxedtogether with 200 ml. of concentrated HCl and 300 ml. of water forhours, then evaporated to dryness and dried in the high vacuum. Thereare obtained 93.6 g. (94.2 percent) oftris-(dihydroxy-phosphonylmethyl)- phosphine oxide as highly viscousoil. The compound shows in the P" NMR spectrum two peaks, namely at 40.7p.p.m. (phosphine oxide) and 16.9 p.p.m. (phosphonyl) in the proportionof 1:3, and in the H'NMR spectrum two peaks, namely at 5.958 8(hydroxyl) and 3.466 8 (two doublets having the coupling constantsphosphine oxide CH 15.6 c.p.s. and phosphonyl Cl-l 20.3 c.p.s. by whichthe structure is ascertained.

Analysis C,H,,O,.,P,

Calcd'lw C 10.85 H 3.64 P 37.32 Found% C 11.61 H 3.97 P 34.56

C 10.18 H 3.60 P 39.28

The acid is very soluble in alcohol and water. 1t forms crystallinesalts of the type OP[CH PO (cyclo-C H NH m.p. 190 C. and OP(CH,PO HNa)-x1-1 O, m.p. 180 C. The last cited salt loses its water at the meltingpoint and then does not melt up to 260 C. Further salts which have beenprepared are:

The acid can be titrated as a hexabasic acid: 1st break at pH 4.4(3equivalents, calcd 110.7-found 111.5); 2nd break at pH 10.7 (3equivalents, calcd 110.7-found 107.5);

EXAMPLE 5 A mixture of 5.9 g. (0.031 mol) of OP(CH Cl) and 45 g. (0.17mol) of P(OC.,H -n);, is heated with stirring at 170 C. and the formedbutyl chloride is continuously distilled off. After 5 hours there areformed 7.7 g. (91.5 percent) of butyl chloride. Now the excess tributylphosphite is distilled off in the vacuum and the residue is dried in thehigh vacuum. There are obtained 18.9 g. (93.5 percent) of crude productyielding 12.5 g. of puretris-(0,0-di-n-butyl-phosphonylmethyl)-phosphine oxide afterrecrystallization from ether; m.p. l09-1 1 1 C. There can be recoveredfurther 4.8 g. of pure compound from the mother-liquor so that the totalyield amounts to 17.3 g. (85.5 percent). The compound shows in the HNMRspectrum three peaks, namely at 0.71 to 28, 2.938 and 4.098, whichascertain the structure of the compound.Tris-(0,0'-din-butyl-phosphonylmethyl)-phosphine oxide is soluble inorganic solvents and insoluble in water. It is therefore also suited asextracting agent for metal salts from aqueous solution.

Analysis C H o l" Ca1cd% C 49.50 H 9.04 P 18.52 moLwcight Found% C 49.02H 9.35 P 111.71 muLwcight 623 (osnmetrically, in benzene) EXAMPLE 6 Amixture of 9.75 g. (0.05 mol) of tri-chloromethyl-phosphine oxide and62.5 g. (0.3 mol) of tri-isopropylphosphite is heated at ll83 C. for 4hours. Within this time there are cleaved 12.7 g. (100 percent) ofisopropylchloride. After having distilled off the excess tri-isopropylphosphite at 7080 C./l0 mm. (28.2 g.), the residue (27.9 g.) solidifiesupon cooling. It is recrystallized from light petroleum. Yield 24.0 g.percent) of tris-(0,0'-di-isopropyl-phosphonylmethyl)-phosphine oxide;m.p. 85-87 C. The compound is soluble in water and in many organicsolvents.

Analysis C H O P Calc'dib C 43.15 H 8.28 P 21.20 mol. weight Found% C43.27 H 8.34 P 21.50 mol. weight 561 (osomctrieally, in benzene) Thecompound shows in the H NMR spectrum three peaks, namely at 2.918 (twodoublets with the coupling constants phosphine oxide-CH 15.8 c.p.s. andphosphonyL-CH, 20.4 c.p.s. 4.788 (multiplet having the couplingconstants POCH 7.9 c.p.s. and H-H 6.1 c.p.s.) and 1.328(couplingconstant HH 6.1 c.p.s.) which ascertains the structure.

The conversion to the corresponding acid can be achieved by thermaldecomposition. 20 g. of the compound are heated at 190 C. There aresplit off 8.6 g. percent) of propene. The acid can be titrated ashexabasic acid and gives the same p" and H NMR spectrum as the acidobtained by hydrolysis with hydrochloric acid.

EXAMPLE 7 A mixture of 5.0 g. (0.026 mol) of OP(CH Cl) 64 g. (0.15 mol)of is heated under reduced pressure (about 100 mg. Hg) at 170-180 C. for4 hours. Thereby g. (88 percent) of 2- ethylhexylchloride distill off.Now the excess phosphite is distilled off in the high vacuum atl130/0.005 mm. As residue there remain 21.5 g. (82 percent) oftris-(0,0'-di-2- ethylhexyl-phosphonylmethyl)-phosphine oxide as viscousoil. The compound is soluble in organic solvents and insoluble in water.

Analysis C H O P (mol. weight 1005.3)

Calc'd7c C 60.93 H 10.83 P 12.32 Found% C 61.40 H l0.50 P 12.10

EXAMPLE 8 A mixture of 4.4 g. (0.02 mol) of di-chloromethyl-phosphinicacid n-butylester and g. (0.08 mol) of tri-n-butylphosphite is heatedwith stirring at 180 and the formed nbutyl chloride is continuouslydistilled off. After 11% hours the theoretical amount of n-butylchloride (3.6 g.) is split off. After the easily volatile products aredistilled off from the reaction mixture, namely 7 g. at 78125 C./10 mm.and 4 g. at 85105 C./0.050.09 mm., there remain as liquid residue 106 g.(98.8 percent) of bis-(0,0'-di-n-butyl-phosphonylmethyl)-phosphinic acidn-butylester, which is pure according to the H'NMR spectrum. Thecompound could not be distilled without decomposition. n,, l.4558.

Analysis c,,H.,o,,P, 534.55

Calcd c 49.43 H 9.24 P 17.38 Found% c 49.21 H 9.03 p 17.44

EXAMPLE9 A mixture of 4.4 g. (0.02 mol) of di-chloromethyl-phosphinicacid n-butylester and 13.3 g. (0.07 mol) of triethylphosphite is heatedwith stirring to 170 C. After 11 hours there are cleaved 2.6 g. (100percent) of ethylchloride. After the easily volatile products aredistilled off from the reaction mixture, namely 4.1 g. at 501l0/10 mm.,there remain as liquid residue 7.8 g. (93 percent) ofbis-(0,0'diethylphosphonylmethyl)-phosphinic acid n-butylester; n1.4580. The HlNMR spectrum ascertains the structure. The compound couldnot be distilled without decomposition.

Analysis C H OJ' (422.32)

Calcdk c 39.81 H 7.88 P 22.0 Found% C 39.21 H 7.78 P 22.47

EXAMPLE 10 EXAMPLE 11 For preparation of the free acid, 15 g. ofbis-(0,0'-diethylphosphonylmethyl)-phosphinic acid ethylester are heatedwith concentrated hydrochloric acid for 40 hours. After concentration byevaporation there remain 10 g. (91 percent) of HO(O)P[CH ,o.,oh. 2H O asviscous liquid. The cyclohexylamine salt melts at 205.2 C. According tothe thermographic analyses and HNMR spectrum it is a dihydrate. The acidcan be titrated as a tetrabasic acid and shows breaks at pH 5.2 (3equivalents calculated for dihydrate 96.6, found 99.2) and at pH 8.8 (1equivalent calcd 290, found 283). According to the total consumption ofacid, the equivalent weight is 73.4 (theory 72.5). The fifth acid groupcould be titrated in aqueous solution after adding NaCl.

EXAMPLE 12 A mixture of 2.4 g. (0.012 mol) of tris-chloromethylphosphine oxide and 9.5 g. (0.037 mol) of diphenylphosphinous acidn-butylester is heated under nitrogen at 170 C. After 30 minutes thereare evolved 2.5 g. of butylchloride and after further heating for anhour totally 3.3 g. (97 percent of hutylchloride. Upon cooling, thereaction mixture solidifies completely. Crude yield 8.6 g. lncompletelyreacted starting material is removed with boiling water. Yield 8.3 g.(97.5 percent) of tris-(diphenyloxophosphinomethyl)-phosphine oxide ofthe formula [(GHs)z,,P( %f Q, m.p. 230 C. (from acetone). TheC(YITPbutld shows in the H'NMR spectrum peaks for PCH P at 3.528(quartet J g; 12.5 c.p.s. Jgpg 15.0 c.p.s. 6H) and C H at 7.568(multiplet, 30H). The spectrum is therefore in agreement with theproposed structure.

EXAMPLE 13 A mixture of 5.7 g. (0.3 mol) of bis-chloromethylphosphinicacid ethylester and 15.8 g. (0.6 mol) of diphenylphosphinous acidn-butylester is heated under nitrogen at 170 C. After 4 hours, there areevolved 4.8 g. (87 percent) of butylchloride. The volatile products aredistilled off at 123-l28 C. /0.1 mm. Upon cooling, the reaction mixturesolidifies. Yield 13 g. (83 percent) ofbis-(diphenyl-oxophosphinomethyl)-phosphinic acid ethylester of theformula CHQCHBO P (O)[CH:P (0) 00110212 8. 0 B b u: d

The compound shows in the H'NMR spectrum peaks for a at 0.798(.l,,,,7c.p.s., b at 3.268(J 13 c.p.s., 1Ppal8 c.p.s.), c at 3.756and dat 7.58.

For the preparation of the free acid, 5 g. of the compound and 20 ml. ofconcentrated HCl are refluxed for 15 hours. The hydrochloric acid isevaporated and the residue recrystallized from alcohol. The acid is awhite solid substance, m.p. 246250 C.

Analysis Equivalent weight calc'd 494.4-l'ound 495.

EXAMPLE 14 A mixture of 3.7 g. (0.023 mol) ofbis-chloromethylmethylphosphine oxide and 14.9 g. (0.09 mol percentexcess) of phosphorous acid triethylester (triethylphosphite) is heatedunder nitrogen at C. After 5 hours, there are released 2.9 g. (98percent) of ethylchloride. Under cooling, the reaction mixturesolidifies totally. The excess triethylphosphite is strongly absorbed bythe formed phosphine oxide and cannot be removed completely in thevacuum. Upon several times recrystallization of the crude product inalcohol-ether, there are obtained 3.2 g. (38.3 percent) of bis-(0,0'-diethylphosphonylmethyl)-methylphosphine oxide of the formula m.p. l02104C.

Analysis C H O.,P, (364.3)

Calcd% C 36.27 H 7.47 Found% C 46.40 H 7.60

EXAMPLE 15 A mixture of 3 g. of bis-chromethyl-ethylphosphine oxide and5.7 g. of phosphorous acid triethylester is heated at 170 C. for 6hours. The theoretical amount (2.2 g.) of ethylchloride is evolved. Theexcess phosphoric acid triethylester is partly distilled off in thevacuum (cf. example 14) and the residue is recrystallized fromalcohol-ether. There are obtained white crystals ofbis-(0,0-diethylphosphonylmethyl)-ethylphosphine oxide of the formulaThe compound shows in the HNMR spectrum peaks for a at 1.348 (.I,,,,7c.p.s., triplet, 12H), b at 4.1758(.l,,,,7 c.p.s., I 8.5 c.p.s., 8H), c2.7088 and 2.788 (two quartets, J 16 c.p.s., Jpfl 20.2 c.p.s.) and d at0.838 to 2.33.

EXAMPLE 16 A mixture of 12.7 g. of bis-chloromethyl-dodecylphosphineoxide (m.p. 57-58 C.) and 26.5 g. of phosphorous acid triethylester isheated at 170 C. for 6 hours. There are released 4.4 g. (84.5 percent)of ethyl chloride. Further heating does no longer yield more ethylchloride. The excess triethylphosphite is distilled off and the residue(17.6 g. 85 percent) recrystallized from alcohol-ether. There areobtained white crystals of bis-(0,0'-diethylphosphonylmethyl)-dodecylphosphine oxide; m.p. 4854' C.

For the preparation of the acid, 6.8 g. of ester are refluxed in methylalcohol and concentrated hydrochloric acid for hours. Then, the mixtureis concentrated by evaporation to dryness (the acid foams verystrongly). There are obtained in quantitative yieldbis-(dihydroxy-phosphonylmethyl)- dodecylphosphine oxide of the formula(I? O 12E251 1 2 0212 The acid shows titration peaks at pH 4 (first andsecond equivalent equivalent weight found 207, calcd 203.1), pH 6.9(third equivalent found 132.5, calcd 135.4) and pH 9.6 (fourthequivalent found 94.2, calcd 101.6).

From the acid there can be prepared a di-, triand tetrasodium salt whichare surface active. The disodium salt melts at 4054 1 0 C.; thetetrasodium salt does not melt until 460 C.

EXAMPLE 17 A mixture of 5.7 g. (0.03 mol) of bis-chloromethylphosphinicacid ethylester and 15.6 g. (0.06 mol) of phenylphosphonous aciddi-n-butylester is heated under nitrogen at 170 C. for 7 hours. Thereare released 4.9 g. (89 percent) of butylchloride. The volatile productsare distilled off (2.2 g., b.p. l05123 C./0.05 mm.). As a residue thereare obtained 13.3 g. (86 percent) ofbis(O-n-butyl-phenylphosphinylmethyl)-phosphinic acid ethylester of theformula CHgCHzOP(O)[CH2P(O)(COHE)(OCH2CH2OHZCH3)12 a c b d e a as acolorless oil; 11,, 1.5318.

Analysis c,.ii,-,o.P, (514.48) Calcd7a c 56.03 H 1.25 P 18.06 Found% c54.01 H 7.03 P 18.11

The compound shows in the H'NMR spectrum peaks for a at 0.66 bis 1.838,b at 2.838 (3.85H), c at 3.918 (6.5H) and d at 7.508 10H).

For the conversion to the corresponding acid, 4 g. of the compound arerefluxed in 20 ml. concentrated HCl for 15 hours and the hydrochloricacid is evaporated. There are obtained 2.2 g. of acid of the formulaHOP(O)[CH P(O)C H )OH] as viscous mass.

Analysis Equivalent weight calc'd l24.8found 119.5.

EXAMPLE 18 A mixture of 3.9 g. (0.02 mol) of tris-chloromethylphosphineoxide and 15.6 g. (0.06 mol) of phenylphosphonous acid di-n-butylesteris heated under nitrogen at 170 C. for 2 hours. There are released 4.5g. (82 percent) of butylchloride. The volatile products (2.3 g., b.p.8593 C./0.05 mm.) are distilled off. The highly viscous residue isdissolved in acetone. An insoluble part is filtered off. Afterevaporation of the acetone there remainstris-(O-nbutyl-phenylphosphinylmethyl)-phosphine oxide of the formula OPlCH P (O) (CBHD) (O CHgCHgCHgCHah b d c a as a colorless oil.

Analysis C H O,P, (680.6)

Calc'd% c 53.23 H 7.11 P 18.20 Found% c 57.80 H 1.34 P 17.56

The compound shows in the H'NMR spectrum peaks for a at 0.668 to 1.838(21H), 12 at 3.108 (6.211), c at 3.958 (5.92H) and d at 7.658 (15H).

For the conversion to the corresponding acid, 5 g. of the compound areheated in 20 ml. of concentrated HCl with addition of ethyl alcohol for15 hours. After concentration by evaporation to dryness the acid OP[CHP(O)(C H )OH] is obtained as white solid residue which softens at andgives a clear melt at 138 C.

Analysis Equivalent weight calcd 170.7, found 173.

EXAMPLE 19 A mixture of 2.5 g. of di-chloromethyl-dodecylphosphine oxideand 4.1 g. of phenylphosphonous acid di-n-butylester is heated at C. for6 hours. There can be recovered 5.4 g. (55 percent) of butylchloride.The volatile products are distilled off..The residue is reprecipitatedin methyl alcohol. There are obtained 4.1 g. (49.5 percent) ofbis-(O-n-butylphenylphosphinyl)-dodecylphosphine oxide as oil.

EXAMPLE 20 A mixture of 4.0 g. of di-chloromethyl-dodecylphosphine oxideand 6.7 g. of diphenylphosphinous acid n-butylester is heated at 170 C.for 3 hours. There can be recovered 1.2 g. (52percent) of butylchloride.The volatile products are distilled off. The remaining (7.7 g.) isrecrystallized in light petroleum. There are obtained 6.8 g. (92.5percent) of bis- (oxodiphenylphosphino)-dodecylphosphine oxide of theformula 0 E 51 HiP 0 021: a b e as a waxylike product.

The compound shows in the HNMR spectrum peaks for a at 0.33 to L666(28H), b at 2.96 and 3.26 (two triplets J,. ,,l2.5 c.p.s., 3.9H) and cat 7.288 (multiplet, 20H).

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A method of inhibiting the precipitation of scale-forming salts in anaqueous system comprising adding to said system a phosphorus compoundcontaining the atom skeleton P-(C-P) or P-(C-P) and corresponding to theformula:

wherein R, R and R signify possibly substituted and/or ethylenically oracetylenically unsaturated hydrocarbon groups or heterocyclic groupsattached through a carbon atom, R groups where R is the group of ahydroxyl compound, HO group or MO group where M is an alkali metal atom,ammonium or substituted ammonium, a is 0 or l, and b is O or I, theamount of said compound added being a threshold amount in a weight ratioof said compound to the cation component of said scale-forming salts notin excess of 0.5 to l and which amount is less than that which wouldcause turbidity removable by a sequestering amount of said compound.

2. A method of claim 1 wherein at least one of R, R and R is an R0, H0or MO group.

3. A method claim I wherein R is hydroxyl, alkyl and alkenyl, R and Rare hydroxyl, alkoxy, alkenyloxy or MO, a is O or 1 and b is 0 or 1; theamount of said compound added being no more than a threshold amount upto about 100 parts per million and is a weight ratio of said compound tothe cation component of said scale-forming salts not in excess of 0.5 tol.

4. A method of claim 1 wherein a is l, b is 0, R and R are hydroxyl orM0; the amount of said compound added being no more than a thresholdamount up to about 100 parts per million and in a weight ratio of saidcompound to the cation component of said scale-forming salts not inexcess of 0.5 to l.

i 5. A method of claim 1 wherein a and b are both 0, R and R arehydroxyl or M0; the amount of said compound added being no more than athreshold amount up to about parts per million and in a weight ratio ofsaid compound to the cation component of said scale-forming salts not inexcess of 0.5 to l.

6. A method of inhibiting precipitation of metal cations from an aqueoussolution containing said cations which coinprises incorporating thereina sequestering quantity of a sequestering agent, phosphorus compoundcontaining the atom skeleton P-(C-P) or P-(C-P) and corresponding to theformula:

wherein R, R and R signify possibly substituted and/or ethylenically oracetylenically unsaturated hydrocarbon groups or heterocyclic groupsattached through a carbon atom, RO groups where R is the group of ahydroxyl compound, HO groups or MO groups where M is a metal atom,ammonium or substituted ammonium, a signifies 0 or 1, and b is 0 or I.

7. A method of claim 6 wherein at least one ofR, R and R is an R0, H0 orMO group.

8. A method of claim 6 wherein R is hydroxyl, alkyl and alkenyl, R and Rare hydroxyl, alkoxy, alkenyloxy or MO, 0 is Oor l andbisOor l.

9. A method of claim 6 wherein a is l, b is O, R is hydroxyl or MO.

10. A method of claim 6 wherein a and b are both 0, R and R are hydroxylor MO.

II. A method according to claim 6 wherein said metal cations arealkaline earth metal cations.

12. A method according to claim 6 wherein said metal cations aretransitional metal cations selected from the group consisting ofdivalent and trivalent metal cations.

13. A method according to claim 12 wherein the metal cation is iron.

2. A method of claim 1 wherein at least one of R1, R2 and R3 is an RO,HO or MO group.
 3. A method claim 1 wherein R1 is hydroxyl, alkyl andalkenyl, R2 and R3 are hydroxyl, alkoxy, alkenyloxy or MO, a is 0 or 1and b is 0 or 1; the amount of said compound added being no more than athreshold amount up to about 100 parts per million and is a weight ratioof said compound to the cation component of said scale-forming salts notin excess of 0.5 to
 1. 4. A methOd of claim 1 wherein a is 1, b is 0, R2and R3 are hydroxyl or MO; the amount of said compound added being nomore than a threshold amount up to about 100 parts per million and in aweight ratio of said compound to the cation component of saidscale-forming salts not in excess of 0.5 to
 1. 5. A method of claim 1wherein a and b are both 0, R2 and R3 are hydroxyl or MO; the amount ofsaid compound added being no more than a threshold amount up to about100 parts per million and in a weight ratio of said compound to thecation component of said scale-forming salts not in excess of 0.5 to 1.6. A method of inhibiting precipitation of metal cations from an aqueoussolution containing said cations which comprises incorporating therein asequestering quantity of a sequestering agent, phosphorus compoundcontaining the atom skeleton P-(C-P)2 or P-(C-P)3 and corresponding tothe formula: P(O)a(R1)b(CH2P(O)(R2)R3)3 b wherein R1, R2 and R3 signifypossibly substituted and/or ethylenically or acetylenically unsaturatedhydrocarbon groups or heterocyclic groups attached through a carbonatom, RO groups where R is the group of a hydroxyl compound, HO groupsor MO groups where M is a metal atom, ammonium or substituted ammonium,a signifies 0 or 1, and b is 0 or
 1. 7. A method of claim 6 wherein atleast one of R1, R2 and R3 is an RO, HO or MO group.
 8. A method ofclaim 6 wherein R1 is hydroxyl, alkyl and alkenyl, R2 and R3 arehydroxyl, alkoxy, alkenyloxy or MO, a is 0 or 1 and b is 0 or
 1. 9. Amethod of claim 6 wherein a is 1, b is O, R1 is hydroxyl or MO.
 10. Amethod of claim 6 wherein a and b are both 0, R2 and R3 are hydroxyl orMO.
 11. A method according to claim 6 wherein said metal cations arealkaline earth metal cations.
 12. A method according to claim 6 whereinsaid metal cations are transitional metal cations selected from thegroup consisting of divalent and trivalent metal cations.
 13. A methodaccording to claim 12 wherein the metal cation is iron.